<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <style>
            * {
                padding: 0;
                margin: 0;
                box-sizing: border-box;
            }
            .center {
                float: left;
                width: 100%;
                height: 300px;
                background: red;
            }
            .left,
            .right {
                float: left;
                width: 200px;
                height: 300px;
                background: gray;
            }
            .left {
                margin-left: -100%;
            }
            .right {
                margin-left: -200px;
            }
        </style>
    </head>
    <body>
        <div class="center"></div>
        <div class="left"></div>
        <div class="right"></div>
    </body>
</html>
